The present invention relates to semiconductor devices and production methods for making same in which semiconductor elements having conductive sections including electrodes for external connection formed thereon.
Semiconductor devices which are mounted on circuit boards of electronic devices are manufactured in such a manner that pins or metallic bumps of lead frames are connected to electrodes for external connection of a semiconductor element on which circuit pattern is formed, and then the whole semiconductor element is encapsulated with resin in a packaging process.
With recent downsizing of electronic devices, semiconductor devices have been becoming even smaller. Special focus has been put on the effort to make semiconductor elements as thin as possible. Thinly machined semiconductor wafers are divided into pieces whereby each has a semiconductor element mounted thereon, and sent individually to a packaging process. Conventionally, prior to the thinning process, in order to enhance their strength of wafers, the wafers are attached to a protective sheet on which pressure sensitive adhesives is coated. After this process, the tackiness of the pressure sensitive adhesives is reduced, and then thinned wafers are removed from the protective sheet.
The thinned semiconductor wafers are, however, vulnerable to external force, thus they can easily be damaged during removal of the protective sheet. Even when the protective sheet is removed without causing any damage, the semiconductor elements tend to suffer problems such as heat cracks generated by thermal stress while they are encapsulated with resin. Thus, it has been difficult to secure reliability of the product. The protective sheets used in the conventional method are consumables and thrown away after one use. This increases waste. As such, the conventional method is not desirable in terms of cost and environmental protection.
The present invention aims at providing highly reliable semiconductor devices and methods of manufacturing the same.
The method of manufacturing a semiconductor device of the present invention includes steps of;
a resin layer forming step in which a face with electrodes of a semiconductor wafer having a plurality of semiconductor elements mounted thereon is coated with a resin layer which has a function of sealing the face; and
a thinning step conducted subsequently, in which the back face of the semiconductor wafer is thinned.
The method of manufacturing the semiconductor device of the present invention further includes a process of forming a conductive section on the electrodes of the semiconductor wafer with a plurality of semiconductor elements in such a manner the conductive section contacts with the electrodes.
The method of manufacturing the semiconductor device of the present invention still further includes a process of cutting the semiconductor wafer having a plurality of semiconductor elements along boundaries of each semiconductor element.
In the thinning process, at least one method selected from a mechanical thinning method, a chemical etching method and a plasma etching method is used.
The semiconductor devices of the present invention are manufactured by the foregoing manufacturing method.
According to the present invention, a face of a semiconductor wafer where electrodes are disposed is coated with a resin layer which seals the face with electrodes, and subsequently, the back face of the semiconductor wafer is thinned by machining. In other words, the semiconductor wafer is reinforced by the resin layer while it is being thinned. Therefore, the semiconductor wafers can be evenly thinned. Further, since the protective sheets are not used, the semiconductor wafers are free of destruction or damage conventionally caused while the protective sheets are being removed. In the same manner, the semiconductor wafers do not suffer damage when the wafers are cut (divided) after the thinning process, since they are reinforced by the resin layer.